On Thu, 14 May 2020 12:06:05 +0300
Sergiu Cuciurean <sergiu.cuciurean@xxxxxxxxxx> wrote:
> As part of the general cleanup of indio_dev->mlock, this change replaces
> it with a local lock on the device's state structure.
> This also changes some internal functions to pass the pointer to the
> state-struct vs a ref to indio_dev just to access the state-struct again.
>
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@xxxxxxxxxx>
Applied to the togreg branch of iio.git.
An observation on this one is that, with the local lock we always
have the iio_priv() structure where we are calling the various
write functions. Those take the indio_dev and use it just to get
the iio_priv(). May be worth a follow up to tidy that up and just
pass the private state structure directly into the various write
functions.
Jonathan
> ---
> drivers/iio/dac/ad5755.c | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/iio/dac/ad5755.c b/drivers/iio/dac/ad5755.c
> index 388ddd14bfd0..7723bd313fc6 100644
> --- a/drivers/iio/dac/ad5755.c
> +++ b/drivers/iio/dac/ad5755.c
> @@ -82,6 +82,7 @@ struct ad5755_chip_info {
> * @pwr_down: bitmask which contains hether a channel is powered down or not
> * @ctrl: software shadow of the channel ctrl registers
> * @channels: iio channel spec for the device
> + * @lock lock to protect the data buffer during SPI ops
> * @data: spi transfer buffers
> */
> struct ad5755_state {
> @@ -90,6 +91,7 @@ struct ad5755_state {
> unsigned int pwr_down;
> unsigned int ctrl[AD5755_NUM_CHANNELS];
> struct iio_chan_spec channels[AD5755_NUM_CHANNELS];
> + struct mutex lock;
>
> /*
> * DMA (thus cache coherency maintenance) requires the
> @@ -174,11 +176,12 @@ static int ad5755_write_ctrl_unlocked(struct iio_dev *indio_dev,
> static int ad5755_write(struct iio_dev *indio_dev, unsigned int reg,
> unsigned int val)
> {
> + struct ad5755_state *st = iio_priv(indio_dev);
> int ret;
>
> - mutex_lock(&indio_dev->mlock);
> + mutex_lock(&st->lock);
> ret = ad5755_write_unlocked(indio_dev, reg, val);
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&st->lock);
>
> return ret;
> }
> @@ -186,11 +189,12 @@ static int ad5755_write(struct iio_dev *indio_dev, unsigned int reg,
> static int ad5755_write_ctrl(struct iio_dev *indio_dev, unsigned int channel,
> unsigned int reg, unsigned int val)
> {
> + struct ad5755_state *st = iio_priv(indio_dev);
> int ret;
>
> - mutex_lock(&indio_dev->mlock);
> + mutex_lock(&st->lock);
> ret = ad5755_write_ctrl_unlocked(indio_dev, channel, reg, val);
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&st->lock);
>
> return ret;
> }
> @@ -211,7 +215,7 @@ static int ad5755_read(struct iio_dev *indio_dev, unsigned int addr)
> },
> };
>
> - mutex_lock(&indio_dev->mlock);
> + mutex_lock(&st->lock);
>
> st->data[0].d32 = cpu_to_be32(AD5755_READ_FLAG | (addr << 16));
> st->data[1].d32 = cpu_to_be32(AD5755_NOOP);
> @@ -220,7 +224,7 @@ static int ad5755_read(struct iio_dev *indio_dev, unsigned int addr)
> if (ret >= 0)
> ret = be32_to_cpu(st->data[1].d32) & 0xffff;
>
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&st->lock);
>
> return ret;
> }
> @@ -246,7 +250,7 @@ static int ad5755_set_channel_pwr_down(struct iio_dev *indio_dev,
> struct ad5755_state *st = iio_priv(indio_dev);
> unsigned int mask = BIT(channel);
>
> - mutex_lock(&indio_dev->mlock);
> + mutex_lock(&st->lock);
>
> if ((bool)(st->pwr_down & mask) == pwr_down)
> goto out_unlock;
> @@ -266,7 +270,7 @@ static int ad5755_set_channel_pwr_down(struct iio_dev *indio_dev,
> }
>
> out_unlock:
> - mutex_unlock(&indio_dev->mlock);
> + mutex_unlock(&st->lock);
>
> return 0;
> }
> @@ -746,6 +750,8 @@ static int ad5755_probe(struct spi_device *spi)
> indio_dev->modes = INDIO_DIRECT_MODE;
> indio_dev->num_channels = AD5755_NUM_CHANNELS;
>
> + mutex_init(&st->lock);
> +
> if (spi->dev.of_node)
> pdata = ad5755_parse_dt(&spi->dev);
> else
